/*
 * Copyright (c) 1999, 2004, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package javax.naming;

/**
 * This class represents a Reference whose contents is a name, called the link name,
 * that is bound to an atomic name in a context.
 * <p>
 * The name is a URL, or a name to be resolved relative to the initial
 * context, or if the first character of the name is ".", the name
 * is relative to the context in which the link is bound.
 * <p>
 * Normal resolution of names in context operations always follow links.
 * Resolution of the link name itself may cause resolution to pass through
 * other  links. This gives rise to the possibility of a cycle of links whose
 * resolution could not terminate normally. As a simple means to avoid such
 * non-terminating resolutions, service providers may define limits on the
 * number of links that may be involved in any single operation invoked
 * by the caller.
 * <p>
 * A LinkRef contains a single StringRefAddr, whose type is "LinkAddress",
 * and whose contents is the link name. The class name field of the
 * Reference is that of this (LinkRef) class.
 * <p>
 * LinkRef is bound to a name using the normal Context.bind()/rebind(), and
 * DirContext.bind()/rebind(). Context.lookupLink() is used to retrieve the link
 * itself if the terminal atomic name is bound to a link.
 * <p>
 * Many naming systems support a native notion of link that may be used
 * within the naming system itself. JNDI does not specify whether
 * there is any relationship between such native links and JNDI links.
 * <p>
 * A LinkRef instance is not synchronized against concurrent access by multiple
 * threads. Threads that need to access a LinkRef instance concurrently should
 * synchronize amongst themselves and provide the necessary locking.
 *
 * @author Rosanna Lee
 * @author Scott Seligman
 * @see LinkException
 * @see LinkLoopException
 * @see MalformedLinkException
 * @see Context#lookupLink
 * @since 1.3
 */

  /*<p>
  * The serialized form of a LinkRef object consists of the serialized
  * fields of its Reference superclass.
  */

public class LinkRef extends Reference {

  /* code for link handling */
  static final String linkClassName = LinkRef.class.getName();
  static final String linkAddrType = "LinkAddress";

  /**
   * Constructs a LinkRef for a name.
   *
   * @param linkName The non-null name for which to create this link.
   */
  public LinkRef(Name linkName) {
    super(linkClassName, new StringRefAddr(linkAddrType, linkName.toString()));
  }

  /**
   * Constructs a LinkRef for a string name.
   *
   * @param linkName The non-null name for which to create this link.
   */
  public LinkRef(String linkName) {
    super(linkClassName, new StringRefAddr(linkAddrType, linkName));
  }

  /**
   * Retrieves the name of this link.
   *
   * @return The non-null name of this link.
   * @throws MalformedLinkException If a link name could not be extracted
   * @throws NamingException If a naming exception was encountered.
   */
  public String getLinkName() throws NamingException {
    if (className != null && className.equals(linkClassName)) {
      RefAddr addr = get(linkAddrType);
      if (addr != null && addr instanceof StringRefAddr) {
        return (String) ((StringRefAddr) addr).getContent();
      }
    }
    throw new MalformedLinkException();
  }

  /**
   * Use serialVersionUID from JNDI 1.1.1 for interoperability
   */
  private static final long serialVersionUID = -5386290613498931298L;
}
